[HADOOP-19229] Vector IO on cloud storage: what is a good minimum seek size?

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 3.4.1
• Component/s: fs/s3
• Labels: pull-request-available
• Assignee: Steve Loughran
• Reporter: Steve Loughran
• Created: 17/Jul/24 19:18
• Updated: 3 days ago 19:17
• Resolved: 02/Jan/25 12:44

Description

vector iO has a max size to coalesce ranges, but it also needs a maximum gap between ranges to justify the merge. Right now we could have a read where two vectors of size 8 bytes can be merged with a 1 MB gap between them -and that's wasteful.

We could also consider an "efficiency" metric which looks at the ratio of bytes-read to bytes-discarded. Not sure what we'd do with it, but we could track it as an IOStat

Issue Links

• Is contained by: HADOOP-19105 S3A: Recover from Vector IO read failures
• links to: GitHub Pull Request #7281